166 
Transactions of the Royal Society of South Africa. 
fourfold grouping of six particles in a ring, bv which every particle is at a 
corner of each of four hexagonal rings of six particles apiece in one plane, of 
which d h m If a is one. 
Note. — For any assigned volume E : C : O = 118 : 105 : 100, 
where E, is the surface of the rhombic dodecahedron, 
where C is the surface of the cube, 
where O is the surface of the octahedron. 
This is perhaps as far as inference, based on mere eye observations of 
fracture, can carry any theory of the internal structure of diamond ; and 
such a theory could only be pi'oximate — in other words, it Could tell us 
B 
f) 
-9- 
a. 
R 
U E 'n H 
Fig. 7. — Grouping of carbon particles in diamond. 
nothing of why the carbon particles should spread in a six-rayed framework, 
nor whether the particles may be regarded as ultimate atoms. A search for 
outside evidence bearing on this point did not at first sight seem to hold out 
much encouragement seeing that most published accounts of the diamond 
are wrong in their facts and, therefore, not likely to be right in their 
theories. Bragg's fundamentally important X-ray work on the structure of 
the diamond (' B. A. Report,' 1913) proved, however, to contain the sort of 
evidence that was required. It was perhaps unfortunate for me that owing 
to various distractions, arising mostly because of the war, I had overlooked 
his results before working out — and writing out as above — my own ; but 
otherwise there is some satisfaction in finding that eye observations alone 
can carry a theory so far as it does. Bragg deduces a somewhat more 
